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Commodore PET 4008 with strange issues?

daver2 said:
It replaces the EDIT ROM (base address $E000).

The reason for this is that this device is generally in a socket - whereas the others had a habit of being soldered into the board.

The EDIT ROM takes care of the localisation for the keyboard and display etc. (in conjunction with a replacement character generator ROM) so was generally socketed.

Dave
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I managed to find some 2716s in the back of the cupboard, but for the life of me can't find the pinout of the edit rom anywhere online (in my machine I believe it to be a mos 901447-29 based on the schematics and where UD8 is on my board, wouldn't be surprised if I'm mistaken) so do any of these sound familiar to you as known compatible?
Hitachi HN462716
TMS2716JL-45
I have one of the HN4262716s and two of the other. I don't yet have anything to burn them with.
Sorry to be so awkward, I did try to find the pinouts myself but no luck and you're objectively the most knowledgeable when it comes to the pet test, thanks again for sticking with it.
 
I should mention, I have no clue if they work, but I doubt they've come to any harm in an IC draw stuffed away in the back of a cupboard at work. Only one way to find out!
 
Do not use any TI TMS2716 parts. They use a Ebb of -5V.

Use can use any 2716 that is compatible with the standard Intel 2716 like the Hitachi, or use the TI 2516 EPROM or equiv.
Oddly you can us a 2732 part if you burn the data into the upper half of that 4K part (because pin 21 is A11 input on the 2732 and always held high in the PET). Or burn the 2K data into both halves of the 4K 2732.
 
Last edited:
Bow,
I just noticed said you don't have a programmer to program the 2716 or 2516 which takes a programming voltage of 25V. An old programmer is usually needed.
Send me your mailing address by the mail system in this forum and I will send you programmed 2716 or 2516 with the daver2 pettest code.

It will be gratis since it is for a PET. Actually I have a PETTEST4 laying around with a checksum of 75DD. I'll have to see if that is the latest version.
 
dave_m said:
Bow,
I just noticed said you don't have a programmer to program the 2716 or 2516 which takes a programming voltage of 25V. An old programmer is usually needed.
Send me your mailing address by the mail system in this forum and I will send you programmed 2716 or 2516 with the daver2 pettest code.

It will be gratis since it is for a PET. Actually I have a PETTEST4 laying around with a checksum of 75DD. I'll have to see if that is the latest version.
Click to expand...
Bless you sir that's a very kind offer, but I'm in the UK and shipping would be absolutely extortionate. Nonetheless, I greatly appreciate the gesture - that sincerely is good of you.

To be truthful, I think it's high time I invested in a programmer anyway, just in case any other ROMs fail in future repairs; I hope this isn't the last PET I'm lucky enough to work on, but hopefully I won't have to bug the forum quite as much going forward!

I'll use the Hitachi HN462716 I found with that in mind, and see if I can get a programmer that's compatible. Might take a while (at the very least I'll have to wait till I'm next paid), but I'll get back to you folks on the results when I do.
Cheers.
 
A GQ-4x programmer will do everything you need for the PET, these are readily available on ebay and a good price.

It is only when you shift to more vintage ROMs with additional power supply requirements like a 2708, that you have to shift to other programmers. A Bytesaver board works well for those, Martin Eberhard made a really convenient program for those. For more vintage parts I have had to move to a BP1400, and in one case an Eberhard programmer for the MM5204.
 
Hugo Holden said:
A GQ-4x programmer will do everything you need for the PET,
Click to expand...
Hugo, knowing you, you would not have stated this unless you have used the GQ-4X with the 2716 and the 2532, the EPROMs needed for pin for pin replacement on the PET.

I did check their compatibility list and at least for their version 4 unit (GQ-4X4), they do list these parts. This seems like an amazing device, a USB interface, works on modern PCs and supports these old 25V Vpp parts! For about $100 USD.
But I would only buy from a reputable source not a far east vendor.
 
dave_m said:
Hugo, knowing you, you would not have stated this unless you have used the GQ-4X with the 2716 and the 2532, the EPROMs needed for pin for pin replacement on the PET.

I did check their compatibility list and at least for their version 4 unit (GQ-4X4), they do list these parts. This seems like an amazing device, a USB interface, works on modern PCs and supports these old 25V Vpp parts! For about $100 USD.
But I would only buy from a reputable source not a far east vendor.
Click to expand...
I was surprised what good value it was. The software disk installed effortlessly (on my HP computer running Windows XP), And it has worked without a hitch ever since. No problem with either 21 or 25V parts.

When I was using it initially, I found that if it was set to a DS1225 Dallas NVram, it also programmed the Ramtron FMw08 FRAM. I notified the manufacturers and after awhile they added that to their supported device list, presumably they confirmed it worked too.

I used it to make a complete set of backup ROMs for the PET (which are in my Pet repair toolkit) as well as for many other ROM related projects, including the ROMs for the RM-65 video card.

And the 2716's for the AIM's Ramrobber:

 
Hugo Holden said:
A GQ-4x programmer will do everything you need for the PET, these are readily available on ebay and a good price.

It is only when you shift to more vintage ROMs with additional power supply requirements like a 2708, that you have to shift to other programmers. A Bytesaver board works well for those, Martin Eberhard made a really convenient program for those. For more vintage parts I have had to move to a BP1400, and in one case an Eberhard programmer for the MM5204.
Click to expand...
Aha, funnily enough that's exactly the configuration I got as a "shot in the dark" second hand off a marketplace seller the other day. Should be in the post now, so I'll give it a go when it arrives. I did check its compatibility with my 27C16s and supposedly it is, according to the documentation - will check that first hand...
 
dave_m said:
Does that little gadget have a boost converter to generate the +25V?
Click to expand...
It must have, as it can program ROMs with either 21 or 25V voltages. It sometimes requests for its external power adapter to be connected, but that is just a 9V@200mA wallwart, most of the time it just runs from the USB power, so it must contain voltage converters to step up to 21 & 25V.
 
The unit arrived the other day and yes indeed, it seems to have a setting for the needed 25V. However, I foolishly assumed that the USB port was for data transmission!
I have most certainly not abandoned this thread, but seem now to be on the "side-quest" of finding a machine that has a working parallel port to connect it up to. I aim to do so by the end of next week, so I'll keep you all updated then.
 
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